This application claims the priority of Korean Patent Application No. 2003-35556, filed on Jun. 3, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to a field effect transistor and a manufacturing method therefore, and more particularly, to a field effect transistor using an insulating vanadium dioxide layer as a channel material, and its manufacturing method.
2. Description of the Related Art
Among transistors, metal oxide semiconductor field effect transistors (MOSFETs) have currently become the leading choice of designers as ultra-small size and high speed switching transistors. MOSFETs employ a double pn-junction structure as a base structure, the pn-junction structure having a linear property at a low drain voltage. As the degree of integration of devices increases, the total channel length needs to be reduced. However, a reduction in a channel length causes various problems such as short channel effects. For example, when a channel length is reduced to approximately 50 nm or less, the size of a depletion layer increases, thereby the density of charge carriers changes, and current flowing between a gate and a channel increases.
To solve these problems, a study has been made on a field effect transistor using a Mott-Hubbard insulator, as a channel material, undergoing a Hubbard's continuous metal-insulator transition, that is, a second-order phase transition. A Hubbard's continuous metal-insulator transition was explained by J. Hubbard, in “Proc. Roy. Sci. (London) A276, 238 (1963), A281, 40-1 (1963)”, and a transistor using the Hubbard's continuous metal-insulator transition is disclosed by D. M. Newns, J. A. Misewich, C. C. Tsuei, A, Gupta, B. A. Scott, and A. Schrott in “Appl. Phys. Lett. 73, 780 (1998).” Transistors using a Hubbard's continuous metal-insulator transition are called Mott-Hubbard field effect transistors or Mott field effect transistors. Mott-Hubbard field effect transistors perform on/off operation according to a metal-insulator transition. In contrast to MOSFETs, Mott-Hubbard field effect transistors do not include any depletion layer, and accordingly, can largely improve the degree of integration thereof. In addition, Mott-Hubbard field effect transistors provide a higher speed switching function than MOSFETs.
On the other hand, similarly to MOSFETs, Mott-Hubbard field effect transistors use a continuous metal-insulator transition. Therefore, when Mott-Hubbard field effect transistors are applied to ultra-small devices, they suffer a problem in that the amount of current decreases due to reduction in the area of devices. This is because charge carriers in general semiconductors are limited to a certain number.